Journal of Sensor Science and Technology (센서학회지)

The Korean Sensors Society (한국센서학회)
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Growth mechanism of three dimensionally structured TiO2 thin film for gas sensors

가스 감응용 3차원 구조체 TiO2 박막 성장기구

  • Moon, Hi-Gyu (Thin Film Material Research Center, Korea Institute of Science & Technology) ;
  • Yoon, Seok-Jin (Thin Film Material Research Center, Korea Institute of Science & Technology) ;
  • Park, Hyung-Ho (Department of Materials science and Engineering, Yonsei University) ;
  • Kim, Jin-Sang (Thin Film Material Research Center, Korea Institute of Science & Technology)
  • 문희규 (한국과학기술연구원 박막재료연구센터) ;
  • 윤석진 (한국과학기술연구원 박막재료연구센터) ;
  • 박형호 (연세대학교 신소재공학과) ;
  • 김진상 (한국과학기술연구원 박막재료연구센터)
  • Published : 2009.03.31
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Abstract

Polystyrene (PS) microspheres were used to good advantage as a template material to prepare macroporous $TiO_2$ thin films. This is enabled to run the thermal decomposition of the PS without the collapsing of the 3-D macroporous framework during the calcination step. $TiO_2$ thin films were deposited onto the colloidal templated substrates at room temperature by RF sputtering, and then samples were thermally treated at $450^{\circ}C$ for 40.min in air to remove the organic colloidal template and induce crystallization of the $TiO_2$ film. The macroporous $TiO_2$ thin film exhibited a quasi-ordered partially hexagonal close-packed structure. Burst holes, estimated to be formed during PS thermal decomposition, are seen as the hemisphere walls. the inner as well as the outer surfaces of the hollow hemispheres formed by the method of thermal decomposition can be easily accessed by the diffusing gas species. As a consequence, the active surface area interacting with the gas species is expected to be enlarged about by a factor of fourth as large as compared to that of a planar films. Also the thickness at neighboring hemisphere could be controlled a few nm thickness. If the acceptor density becomes as large that depletion width reaches those thickness, the device is in the pinch off-situation and a strong resistance change should be observed.

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